Embodiments of the present technology generally relate to ultrasonic imaging. More particularly, embodiments of the present technology relate to reduction of multiline artifacts in Doppler imaging.
Doppler imaging uses reflected ultrasound waves to evaluate blood as it flows through a blood vessel. Doppler imaging can be used to evaluate blood flow through arteries and veins. Doppler imaging can indicate blocked or reduced blood flow through narrowed arteries, which can lead to a stroke. Doppler imaging can also reveal blood clots in veins that could break loose and block blood flow.
During Doppler imaging, a handheld instrument (transducer) is passed over the skin above a blood vessel. The transducer sends and receives ultrasound waves. The ultrasound waves bounce off solid objects, including blood cells. Movement of blood cells can cause a change in pitch of the reflected sound waves (called the Doppler effect). If there is no blood flow, the pitch does not change. Information from the reflected sound waves can be processed to provide graphs or pictures that represent the flow of blood through the blood vessels.
Types of Doppler imaging include, for example, continuous wave Doppler, duplex Doppler, color flow, power Doppler and B-flow. In color flow imaging, ultrasound signals are converted into colors that are overlaid on an image of a blood vessel, and the colors represent speed and direction of blood flow through the vessel.
Increasing the frame rate in ultrasonic imaging is desirable. Parallel receive beams can be used to increase the frame rate during multiline image acquisition. However, using parallel receive beams can introduce artifacts in images, for example, due to misalignment of transmit and receive beams. The trade-off between frame rate and image quality can lead to suboptimal images for medical diagnosis.
Needless to say, forming a best possible image for different anatomies and patient types is important to diagnostic imaging systems. Poor image quality may prevent reliable analysis of an image. For example, a decrease in image contrast quality may yield an unreliable image that is not usable clinically. Additionally, the advent of real-time imaging systems has increased the importance of generating clear, high quality images.
Techniques aimed at improving image quality during multiline image acquisition have been proposed, for example, in U.S. Pat. No. 6,482,157, issued to Robinson on Nov. 19, 2002, and the article “Parallel Beamforming Using Synthetic Transmit Beams,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 54, No. 2, February 2007. As discussed herein, it has been found that such proposed techniques are of limited effectiveness in connection with Doppler imaging.
A method and apparatus for multiline color flow and angio ultrasound imaging aimed at improving image quality is suggested in International Publication No. WO 2008/068709 A1, which names Clark and was published on Jun. 12, 2008. However, the International Publication does not disclose the techniques disclosed herein.
Thus, there is a need for improved systems and methods that can reduce multiline artifacts in Doppler imaging.